Conventional building windows suffer from numerous limitations in light modulation, thermal insulation, and energy utilization, struggling to meet the dual demands of modern buildings for high energy efficiency and consistent thermal comfort. In response to the various stages of energy loss through windows, a design concept for a hydrogel-based smart material that dually regulates solar transmittance and infrared emissivity has been proposed. Stimulated by temperature or humidity, this hydrogel can achieve significant changes in visible light transmittance (86.8 %) and infrared emissivity (50.1 %) autonomously and independently, exhibiting excellent solar modulation capability (78.7 %) and controllable radiative cooling performance (switching between a heat dissipation layer and an insulation layer). The hydrogel exhibits passive response to dual stimuli either independently or synergistically, with the capability to restore its initial properties through active interventions such as water mist spraying. In various application conditions, indoor temperatures and window surface temperatures can be reduced by up to 23.1°C and 13.2°C, respectively. Moreover, simulation results indicate that this design can be applied across various climatic zones globally (achieving annual energy savings of 2.6 % - 55.9 %), providing new design ideas and technical directions for building energy saving.
Shaojun Chen,Zhankui Mei,Huanhuan Ren,Haitao Zhuo,Jianhong Liu,Zaochuan Ge
This paper reports a new type of zwitterionic polyurethane containing pyridine type zwitterionic segments for shape memory materials. The pyridine type zwitterionic shape memory polyurethanes (SMPUs) were synthesized using polyurethane polymerization from N,N-bis(2-hydroxylethethyl)isonicotinamide (BINA), hexamethylene diisocyanate (HDI), diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BDO), followed by a ring-opening reaction with 1,3-propanesultone (PS). The structure and properties of the pyridine-type zwitterionic SMPUs (PyZPUs) were investigated systematically. The results demonstrate that the PyZPUs form phase-separation structures composed of a hard phase and an amorphous soft phase with a broad glass transition. The shape memory tests show that the PyZPUs have thermal-induced dual-shape memory effects (SMEs), triple-SMEs and quadruple-SMEs and also moisture-sensitive SMEs. Comparatively, the samples with PS/BINA molar ratios of 0.6–0.8 have more than 86% shape recovery and more than 95% shape fixity with a heat stimulus. Under moisture conditions, these samples also show the quickest moisture-sensitive strain recovery, up to 86%. Moreover, the PyZPUs show good biocompatibility when the content of pyridine type zwitterionic segments is beyond 21 wt%. Thus, the PyZPUs are expected to have many promising applications in smart biomedical fields.
危险品化学品经营许可证（带存储）